Characterization of CN x films prepared by reactive magnetron sputtering

Abstract

Carbon nitride film was prepared on silicon substrate by an rf magnetron sputtering with a graphite target. Nitrogen–argon mixture gas was employed. To investigate effect of ion bombardment on film hardness, negative bias voltage was applied on the substrate, and a gas flow ratio of argon to nitrogen was changed. The rf power was kept at 300 or 650 W. The film was characterized by XPS, a microhardness tester, FTIR and Raman spectroscopy. Atomic ratio of the film, N/C, had a range from 0.3 to 0.7. Knoop hardness of the film increased with increase in the negative bias voltage, gas flow ratio and rf power. The ratio of 3-dimensional structure (tetrahedral C–N bond to total bonds) was estimated from FTIR spectra. With the increase of ion energy and incoming ion flux, the component of 3-dimensional structure increased. The hardness of the film proportionally increased with the ratio of 3-dimensional structure.